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DB_FILE_MULTIBLOCK_READs and Extent boundaries -- was RE: db

From: Hemant K Chitale <hkchital_at_singnet.com.sg>
Date: Thu, 20 Mar 2003 00:55:52 +0800
Message-Id: <24715.322395@fatcity.com>


See Note 181272.1 on MetaLink.
"The Multiblock I/O never spans Extent Boundaries even if the Extents   are continuous and also if using Locally Managed Tablespaces. " Hemant

At 07:44 AM 17-03-03 -0800, you wrote:
>How can you tell that DB_FILE_MULTIBLOCK_READ will not span extents?
>I was unable to confitrm that on Metalink.
>
> > -----Original Message-----
> > From: Hemant K Chitale [mailto:hkchital_at_singnet.com.sg]
> > Sent: Monday, March 17, 2003 9:44 AM
> > To: Multiple recipients of list ORACLE-L
> > Subject: Re: db file scattered read
> >
> >
> >
> > If 14706+3 is one extent and another extent begins at 14710,
> > it will NOT read
> > 14706+8. A DB_FILE_MULTIBLOCK_READ will not span extents.
> > Hemant
> >
> > At 09:04 AM 14-03-03 -0800, you wrote:
> > >Here is a part of trace file . I am finding that oracle is
> > trying to read
> > >8 or 3 or 7 blocks at a time . But block numbers are all
> > sequential i.e.
> > >it will read 3 blocks starting from 14706 and then 8 blocks
> > starting from
> > >14710 ( 14706+3 ). Why it doesn't read 8 blcoks always it
> > multi_block_read
> > >is set to 8 ? Any Idea .
> > >Also what is ela=1 ,does it mean elapsed time is 1 sentisec ?
> > >
> > >
> > >
> > >WAIT #32: nam='db file scattered read' ela= 0 p1=4 p2=14706 p3=3
> > >WAIT #32: nam='db file scattered read' ela= 1 p1=4 p2=14710 p3=8
> > >WAIT #32: nam='db file scattered read' ela= 2 p1=4 p2=14718 p3=8
> > >WAIT #32: nam='db file scattered read' ela= 0 p1=4 p2=14727 p3=3
> > >WAIT #32: nam='db file scattered read' ela= 0 p1=4 p2=14731 p3=7
> > >WAIT #32: nam='db file scattered read' ela= 1 p1=4 p2=14739 p3=3
> > >WAIT #32: nam='db file scattered read' ela= 1 p1=4 p2=14744 p3=8
> > >WAIT #32: nam='db file scattered read' ela= 1 p1=4 p2=129784 p3=8
> > >
> > >
> > >Thanks
> > >-ak
> >
> > Hemant K Chitale
> > My personal web site is : http://hkchital.tripod.com
> >
> >
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.net
> > --
> > Author: Hemant K Chitale
> > INET: hkchital_at_singnet.com.sg
> >
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Received on Wed Mar 19 2003 - 10:55:52 CST

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